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A076460 Sum of squares of numbers that can be written as t*n + u*(n+1) for nonnegative integers t,u in exactly one way. 5
1, 103, 1130, 6070, 22355, 64981, 160468, 351660, 703365, 1308835, 2297086, 3841058, 6166615, 9562385, 14390440, 21097816, 30228873, 42438495, 58506130, 79350670, 106046171, 139838413, 182162300, 234660100, 299200525, 377898651, 473136678, 587585530, 724227295 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

Fred. Schuh, Vragen betreffende een onbepaalde vergelijking, Nieuw Tijdschrift voor Wiskunde, 52 (1964-1965) 193-198.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = n*(n+1)*(7*n^4+2*n^3-6*n^2-n+1)/6.

G.f.: x*(1+96*x+430*x^2+288*x^3+25*x^4)/(1-x)^7.

MAPLE

seq(1/6*n*(n+1)*(7*n^4+2*n^3-6*n^2-n+1), n=1..30);

MATHEMATICA

CoefficientList[Series[(1 + 96 x + 430 x^2 + 288 x^3 + 25 x^4)/(1 - x)^7, {x, 0, 50}], x] (* Vincenzo Librandi, Dec 30 2013 *)

PROG

(MAGMA) [n*(n+1)*(7*n^4+2*n^3-6*n^2-n+1)/6: n in [1..50]]; // Vincenzo Librandi, Dec 30 2013

CROSSREFS

Cf. A076389, A076461-A076465.

Sequence in context: A023355 A113629 A034180 * A245495 A097726 A262273

Adjacent sequences:  A076457 A076458 A076459 * A076461 A076462 A076463

KEYWORD

easy,nonn

AUTHOR

Floor van Lamoen, Oct 13 2002

EXTENSIONS

More terms from Vincenzo Librandi, Dec 30 2013

STATUS

approved

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Last modified December 12 12:30 EST 2019. Contains 329958 sequences. (Running on oeis4.)